call/cc sum1-n, reverse

(call/cc identity) が、なるほど！だったので。

• 各言語で作った簡易足し算器

	;; http://www.rakunet.org/TSNET/topics/compare.html#scheme
	(define (sum1-n n)
	(let ((total 0)
	(i 0))
	(let1 next (call/cc identity)
	(if (< n i)
	total
	(begin
	(set! total (+ total i))
	(set! i (+ i 1))
	(next next))))))
	(sum1-n 10)
	(define (sum1-n n)
	(let ((total 0)
	(i 0))
	(let/cc break
	(let1 next (call/cc identity)
	(if (< n i)
	(break total)
	(begin
	(set! total (+ total i))
	(set! i (+ i 1))
	(next next)))))))
	(sum1-n 10)
	; -> 55

view raw callcc-sum1-n.scm hosted with ❤ by GitHub

	;; reverse
	(define (my-reverse ls)
	(let ((ls ls)
	(acc '()))
	(let/cc return
	(let1 next (call/cc identity)
	(if (null? ls)
	(return acc)
	(begin
	(set! acc (cons (car ls) acc))
	(set! ls (cdr ls))
	(next next)))))))
	(my-reverse '(1 2 3 4 5))

view raw callcc-reverse.scm hosted with ❤ by GitHub

• vallog: memo, call/cc, named let, do
• vallog: TSS let/cc, try